RTHD and RTAC - Trane

Load
Unload
Compressor Capacity - RTHD
Table 8. Possible Causes to Loading Problem
3. Place the chiller in ”Auto” mode and provide all necessary interlocks and a
load to start the chiller
4. Allow the compressor to start and monitor the compressor currents with a
clamp-on type ammeter.
1. Once the compressor has started, allow the Unload solenoid to remain
energized for approximately 45 seconds, then manually load the compressor
(using UCP2 or TechView). Record the male piston pressure and compressor
currents.
2. Monitor the male pressure behind the piston and the amp draw of the unit.
Both should gradually increase with each pulse of the load solenoid.
Note: All limits are still active. If the chiller enters into a condenser, current, or
evaporator limit. Continuously monitor the operating mode.
1. Manually Unload the compressor using the front panel or TechView.
2. The pressure behind the male piston and the RLA of the unit should gradually
decrease with each pulse sent to the unload solenoid.
Note: The pressure behind the piston should be approximately suction pressure
when the compressor is fully unloaded. The RLA will be dependent on the
application.
With the results from the above checkout procedure use Table 8 to determine
the possible causes of the loading problem..
Possible Operation
Recorded
Measurement Load Unload Hold
Operating properly Piston Pressure increase decrease remain constant
Amp Draw increase decrease remain constant
Stuck piston Piston Pressure increase decrease remain constant
Amp Draw remain constant remain constant remain constant
Leaking load solenoid, Piston Pressure increase may drop initially but increase
internal leak or leaking
will increase as soon
piston
as the unload is deenergized
Amp Draw increase may drop initially but
will increase as soon
as the unload is de
energized
increase
Leaking unload solenoid Piston Pressure remain constant or
decrease
decrease decrease
Amp Draw remain constant or
decrease
decrease decrease
RLC-SVD05A-EN 47